There are devices whose safeness is/are warranted by those methods.

The verb in question is attributed to "safeness". "safeness" is singular, so it requires "is". But "devices" is plural. So?

closed as off-topic by Jason Bassford, Andrew, choster, shin, Chenmunka Jun 25 at 10:05

This question appears to be off-topic. The users who voted to close gave this specific reason:

  • "This question should include more details than have been provided here. Please edit to add the research you have done in your efforts to answer the question, or provide more context. See: Details, Please." – Jason Bassford, Andrew, choster, shin, Chenmunka
If this question can be reworded to fit the rules in the help center, please edit the question.

  • 6
    We don't actually use safeness in such contexts (it's safety). But either way, since the referent is a singular noun the verb form must be is. The plural verb form are has already been correctly applied to the primary subject There are devices... – FumbleFingers Jun 17 at 16:43

The subject is safeness (or, rather, safety, as FumbleFingers says), so the verb needs to be singular.

There are similar cases where usage doesn't always follow this logic, but in such cases the verb usually agrees with the closest noun phrase to the verb, even if that is not the logical subject. Here the logical subject is the closest noun phrase to the verb, so that issue will not appear, and any native speaker would say "is">

Not the answer you're looking for? Browse other questions tagged or ask your own question.